Wal-Mart decided to pay the company's January 2 dividend of 39.75 cents a share a few days early on December 27th. In doing so, the Walton family will pay a 15% dividend tax on their $636 million in proceeds. That will amount to $95 million in 2012.

Had the company waited a few days and dividend taxes on the wealthiest Americans jumped to 43.4%, the Walton's tax bill could run as high as $276 million.

A spokesperson for Wal-Mart said the three Waltons on its board of directors recused themselves from the decision to pay the dividend in 2012 instead of 2013. A spokesperson for the Walton family did not return a call for comment.